A successful infiltration of al Qaeda in the Arabian Peninsula by a Saudi intelligence agent with CIA oversight will be hailed in Washington as a major success, but it begs an important question: if the operations of the bomb maker, Fahd Mohammed Ahmed al-Quso, could be tracked so closely, why couldn’t he have been arrested instead of killed by a drone strike?

The supposed rationale for assassinating suspected terrorists by remote control is that they are so elusive and operate in such inaccessible locations that capture is impossible. It’s hard to imagine how this could have been the case with al Quso. He must effectively have been under surveillance and rather than make use of what might have been multiple opportunities to arrest him, the CIA apparently decided there was no need — he could simply be eliminated whenever necessary.

As a battlefield practice, take no prisoners is considered a war crime. For the Obama administration it has become standard procedure — and a procedure that the American journalists virtually never question.

The New York Times reports: The would-be suicide bomber dispatched by the Yemen branch of Al Qaeda last month to blow up a United States-bound airliner was actually an intelligence agent for Saudi Arabia who infiltrated the terrorist group and volunteered for the suicide mission, American and foreign officials said Tuesday.

In an extraordinary intelligence coup, the double agent left Yemen, traveling by way of the United Arab Emirates, and delivered both the innovative bomb designed for his air attack and critical information on the group’s leaders to the C.I.A., Saudi and other foreign intelligence agencies.

After spending weeks at the center of the terrorist network’s most dangerous affiliate, Al Qaeda in the Arabian Peninsula, the agent provided critical information that permitted the C.I.A. to direct the drone strike on Sunday that killed Fahd Mohammed Ahmed al-Quso, the group’s external operations director and a suspect in the bombing of the American destroyer Cole in Yemen in 2000.

He also handed over the bomb, designed by the group’s top explosives expert to be invisible to airport security, to the F.B.I., which is analyzing its properties.

Officials said the agent, whose identity they would not disclose, works for the Saudi intelligence service, which has cooperated closely with the C.I.A. for several years against the terrorist group in Yemen. He operated in Yemen with the full knowledge of the C.I.A., but not under its direct supervision, the officials said.

The agent is now safe in Saudi Arabia, officials said. The bombing plot was kept secret for weeks by the C.I.A. and other agencies because they feared retaliation against the agent and his family.